A variety of active bleaching compositions are known including active halogen bleaches. Active halogen compositions have been used for many years in a variety of cleaning or sanitizing methods. Such halogen sources can come in the form of gases (gaseous Cl2, Br2, etc.), liquids (aqueous sodium hypochlorite), or solids, calcium hypochlorite, chlorinated sodium tripolyphosphate, chlorinated isocyanuric acid and others. Solids can be dissolved in water to create a bleach concentrate. Such materials can be applied to processing by metering a gas or liquid form of the halogen source into the wash site into an aqueous stream directed to the wash site. Solid halogen sources can be used in a variety of washing processes by adding solids directly to the washing liquor or by metering an aqueous solution of the chlorine source into the wash locus.
Solid sources of halogen bleaches have been used in both aqueous solutions, particulate powders or in solid tablet or brick form. The solid tablet or brick form of the solid active bleach source can pose a problem in control of dispensing. Tablets or bricks of the material are introduced into aqueous dispensers. The dispensers can be calibrated to provide various bleach concentrations, often to provide 1 to 10 grams of halogen per bleach cycle. Within the dispenser the tablet or tablets are fixed mechanically at a fixed distance from an aqueous spray. As the aqueous spray contacts the surface of the solid bleach material the water dissolves a portion of the bleach source creating a liquid concentrate solid which is directed to a wash/bleach cycle. However, water can be absorbed by the tablet and can soak through the entire tablet or brick. The water can pass through this brick and can pass further into adjacent tablets or bricks. The absorbed water can cause the tablet(s) or brick(s) to become cracked, split, crumbled or become “slushy”. Such water soaked tablets often become difficult to dispense with adequate control of bleach concentrate in the wash liquor. Parts of the tablet can randomly be released by a disintegrating tablet causing random dispensing of undesirable, harmful, substantially large concentrations of halogen into the washing site. In the instance that the slushy or cracked tablet releases a substantial proportion of its mass into the dispenser, the dispenser can release 100–300 grams or more of chlorine source into the washing locus. Such high concentrations of chlorine can cause metal corrosion to washer or dispenser, fabric damage, color change or other harmful results.
The encapsulation of active sources of halogen bleach with organic and inorganic coatings have been disclosed in Brubaker, U.S. Pat. No. 4,279,764; Brennen, U.S. Pat. No. 3,637,509; Idudson, U.S. Pat. No. 3,650,961; Alterman, U.S. Pat. Nos. 3,983,254 and 3,908,045. Olson, U.S. Pat. No. 4,681,914, teaches the use of encapsulated sources of active halogen in cast solid warewashing detergents. In Olson, the encapsulated halogen source is dispersed in a molten caustic material that solidifies to form a sodium hydroxide based warewashing material.
Accordingly, a substantial need exists in processes using aqueous sources of halogen to provide a solid halogen source that can dispense a uniform proportion of the solid mass of the halogen source without uncontrolled dispensing problems.